“You see the Earth has a 35 year thermal inertia and so what we’re doing now is only the beginning because we’re waiting 35 years even to see the effects of what we did 35 years ago. So it would be another 30 years until we started to really see, even at the only 380 parts per million level [of C02-e atmospheric concentration] that we’re doing now, what those effects are. And we’ll be at 550 [parts per million of C02-e concentration] by then — or more — and it’s never been above 300. So there’s a serious debate over whether that will be very bad or not, very bad, but all we know is no matter what we do when we get there there’s no turning back.”

Climate Forcing From Cosmic Rays Much Higher Than IPCC Estimate
In a paper that has been accepted for publication in the Indian science journal Current Science, physicist Dr U R Rao argues that decreasing cosmic ray activity accounts for almost 40 % of global warming. This is much higher than the cosmic ray contribution in the IPCC model.

Below is an extract from the January 21 article on Rao's paper in The Hindu:

"According to the latest report by the IPCC, all human activity, including carbon dioxide emissions, contribute 1.6 watts/sq.m to global warming, while other factors such as solar irradiance contribute just 0.12 watts/sq.m.

However, Dr Rao's paper calculates that the effect of cosmic rays contributes 1.1 watts/sq.m, taking the total contribution of non-human activity factors to 1.22 watts/sq.m.

This means that increased carbon dioxide emissions in the atmosphere are not as significant as the IPCC claims. Of the total observed global warming of 0.75 degrees Celsius, only 0.42 degrees would be caused by increased carbon dioxide. The rest would be caused by the long term decrease in primary cosmic ray intensity and its effect on low level cloud cover.

This means that predicting future global warming and sea level rise is not as simple as the IPCC makes it to be, since it depends not only on human activity, but also significantly on the unpredictability of cosmic ray intensity.

“We conclude that the contribution to climate change due to the change in galactic cosmic ray intensity is quite significant and needs to be factored into the prediction of global warming and its effect on sea level raise and weather prediction,” says the paper."

I commend the response at the end by V. Ramanathan of Scripps Institute. I thought this was interesting for instance:

Trends in GCRs and Global Mean
Temperatures: Observations of global average
temperatures during the twentieth century, reveal 3 basic
periods: A) Warming trend from 1900 to 1940; B) followed
by a slight cooling trend from 1940 to 1970; C) which
terminated in the current rapid warming trend which is
continuing unabated until now. Keeping this pattern in
mind, if we examine Figure 1 of Rao
we note that GCRs
(top two panels) underwent a monotonic decrease in
intensity from 1900 to about 1970 and then leveled off
from 1970 onwards (revealed more clearly in the middle
panel). Clearly, the variations in GCRs can not account for
the large warming trend from 1970 to 2010.[my emphasis]

And note: even if Rao's hypothesis proved to be correct, it merely underlines the urgency of stopping the addition of more radiative forcing to the system via the injection of billions of tonnes of CO2, methane, etc. There's no get out of jail free card.

It's interesting that cosmic ray proton ionization causes cloud condensation. My old boss used to say as we discussed shit over our liquid lunch before he went back to give afternoon lectures, that when there's a buildup of escaped radon, which is normally inert, that some ions must be negatively charged and that there's a sudden atmospheric inversion causing abrupt wet weather